Embodiments of the application described herein relate to a semiconductor memory, and more particularly, relate to a nonvolatile memory device, a memory controller, and a nonvolatile memory system including the nonvolatile memory device and the memory controller.
A semiconductor memory device is a storage device which is fabricated using semiconductors such as, but not limited to, silicon (Si), germanium (Ge), gallium arsenide (GaAs), and indium phosphide (InP). Semiconductor memory devices are classified into a volatile memory and a nonvolatile memory.
The volatile memory may lose contents stored therein at power-off. The volatile memory includes the following: a static RAM (SRAM), a dynamic RAM (DRAM), and a synchronous DRAM (SDRAM). The nonvolatile memory may retain stored contents even at power-off. The nonvolatile memory includes the following: a read only memory (ROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory, a phase-change RAM (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), and a ferroelectric RAM (FRAM).
The flash memory is used in various fields thanks to the following advantages: mass storage, low noise, and low power. The flash memory stores data by changing threshold voltages of memory cells. The flash memory device reads stored data by sensing threshold voltages of memory cells using predetermined read voltages. An error may occur at data stored at the flash memory device due to various factors. In recent years, there have been developed various techniques for recovering such errors.